Byron Trott is leaving Goldman Sachs to start his own merchant-banking firm to be called BDT Capital Partners.

Buffett tells the WSJ, "We'll have a modest partnership interest.. We will not be the big dog."

Buffett says people who have worked with Trott in the past will probably invest in his new fund. The Journal says the fund will invest in "family-controlled and entrepreneurial companies" and "could grow to about $2 billion."

And back in his 2003 letter to Berkshire shareholders, Buffett wrote of Trott: "He understands Berkshire far better than any investment banker with whom we have talked and – it hurts me to say this – earns his fee."